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The coexistence curves of liquid-liquid equilibrium (LLE) for the mixtures: phenylacetonitrile + heptane, + octane, + nonane, + cyclooctane, or + 2,2,4-trimethylpentane and for 3-phenylpropionitrile + heptane, or + octane are reported. Aromatic nitrile + alkane, + aromatic hydrocarbon or + 1 alkanol systems are investigated using a set of thermophysical properties: phase equilibria (solid-liquid, SLE, vapour-liquid, VLE and LLE), excess molar functions, enthalpies (E m H), isochoric internal energies (E Vm U), isobaric heat capacities (E pm C) and volumes (E m V), and the Kirkwood's correlation factor. Due to proximity effects between the phenyl and the CN groups, dipolar interactions between molecules of aromatic nitriles are stronger than those between molecules of isomeric linear nitriles. Dipolar interactions become weaker in the order: 3-phenylpropionitrile > phenylacetonitrile > benzonitrile. Benzonitrile + aromatic hydrocarbon mixtures are characterized by dispersive interactions and structural effects. The latter are more important in systems with phenylacetonitrile. Structural effects are also present in benzonitrile + n-alkane, or + 1-alkanol + mixtures. The systems mentioned above have been studied using DISQUAC. Interaction parameters for contacts where the CN group in The E m V curves of solutions with longer 1-alkanols are more poorly described, which has been explained in terms of the existence of structural effects.

Values of density (ρ), speed of sound (c) and refractive index (n D) for N,N-dimethylformamide (DMF) + N-propylpropan-1-amine (DPA) or + butan-1-amine (BA) mixtures at (293.15−303.15) K, and for DMF + N-butylbutan-1-amine (DBA) or hexan-1-amine (HxA) mixtures at 298.15 K are reported. Density and speed of sound measurements were conducted using a vibrating-tube densimeter and sound analyser, Anton Paar model DSA5000; refractive index values, n D values were obtained by means of a RFM970 refractometer from Bellingham+Stanley. The experimental ρ, c and n D values have been used to determine excess molar volumes, V m E, excess adiabatic compressibilities, κS E, excess speeds of sound, c E, excess thermal expansion coefficients, α p E, and excess refractive indices, n D E. This set of data shows the existence of interactions between unlike molecules and of structural effects in the mixtures under study. V m E values of solutions including linear secondary amines are lower than those of mixtures with linear primary amines. In fact, the contribution to V m E from the breaking of amine−amine interactions is larger for the latter systems. Calculations on Rao’s constant point out that there is no complex formation between the mixture components. Dispersive interactions have been analyzed by means of the molar refraction. It is shown that solutions with DPA or HxA are characterized by similar dispersive interactions and that they mainly differ by dipolar interactions.

Thermodynamics of mixtures with strongly negative deviations from Raoult's law. XV. Permittivities and refractive indices for 1-alkanol + n-hexylamine systems at (293.15-303.15) K. Application of the Kirkwood-Fröhlich model

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